Apparatus for changing coating solutions of coating machines



March 7, 1950 Filed Sept. 28, 1945 P. MOREY 2,500,041 APPARATUS FORCHANGING COATING SOLUTIONS OF COATING MACHINES 2 Sheets-Sheet 1 FIG].

LEON P. M OREY INVENTOR j: ATTORNE S March 7, 1950 L. P. MOREY 2,500,041

APPARATUS FOR CHANGING COATING SOLUTIONS OF COATING MACHINES Filed Sept.28, 1945 2 Sheets-Sheet 2 FIG. 5.

LEON P. MORE) INVENTOR BY W M ArroRNmzs Patented Mar. 7, 1950 UNITEDSTATES PATENT OFFICE APPARATUS FOR CHANGING COATING SOLUTIONS OF COATINGMACHINES Leon P. Morey, Rochester, N. Y., aollgnor to Eastman KodakCompany, Rochester, N. Y.. a corporation of New Jersey ApplicationSeptember 28, 1945, Serial No. 819,031

18 Claims. (Cl. 91-46) The present invention relates to the art ofcoating a continuous web, and particularly to an apparatus for replacinga pan of coating solution with another very rapidly without causing anoticeable agitation in the surface of the solution in the pan movinginto coating position.

In known coating procedures the supply of coating solution is containedin a pan from which it is taken directly by the web be'ng immersedtherein or by an applicator, or pick-up, roll immersed therein. In allinstances the pan is constantly supplied with solution to maintain thelevel of the solution in the pan constant, or Practically so. In thewell known immersion method of coatng, the constancy of this level inthe coating pan is very critical as to the thickness of coating suppliedto the web and elaborate steps are taken to maintain the level in thecoating pan constant. It is also imperative that the surface of thesupply of coating solution be absolutely free of ripples at all timessince such ripples have the same effect as changes in the level of thecoating solution, namely, cause changes in thickness of the coatingbeing applied to the web.

It is oftcn desirable, or necessary, for a number of different reasons,to change a given coating solution for a new one, and it is desirable tobe able to do t is without shutting down the machine, and particularlywithout stopping the feed of the web; because this necessarily means acut in production. At present, a change of the coating solutionnecessitates a shut-down of the machine and a compl te cleaning of thecoatin pan and refilling it with the solution which takes a conslderabletime. The reasons for changing the coat ng solution are too numerous tocompletely list herein but a few representative ones might be mentioned.First, the most obvious one is to substtute an entirely differentcoating solution for the one being used. Secondly, certain solutions,despite the fact that they are vigorously agit ted and repeatedly addedto, change in physical and chemical properties with time and have to bethrown away and replaced by a new batch. Thirdly, the solution mightbecome contaminated in some way during the coating operat on which wouldmean a complete clean-up oi the coating pan.

One object of the present invention is to provide for interchangingcoating solutions by having two or more coating pans which can be filledwith the desired coating solution. and substituting one complete pan foranother when it is desired to change the coating solution.

Another object is to provide an arrangement 2 wherein the severalcoating pans are movable between a coating position and a readyposition, and whereby two pans can be interchanged rapidly andsimultaneously with no eflort on the part of the operator except to pusha switch button.

And yet another object is to provide an arrangement whereby one coatingpan is removed from, and another is moved to, the coating positionrapidly and simultaneously so that no stopp e of the web feed isrequired.

And still another object is to provide a coating pan interchangemechanism which moves a coating pan to the coating position in such away that no disturbance of the solution of the pan is caused which isdetectable in the quality of the final coating of the web. In otherwords, the constant liquid level is maintained in the pan at all timesor is present by the time the pan reaches the coating position.

And another object is to provide a. pan interchange mechanism in whichthere is substantially a static balancing of the pans and the operatinglinkage therefor in all positions of movement.

And another object is to provide a Dan interchange mechanism which isdriven by a cam the curve of the working face of which is such as toimpart uniform acceleratin and decelerating motions to the pans duringthe interchange.

And a further object is to provide a pan interchange mechanism in whichthe coating pans are positively located in the coating position by thecooperation between adjustable stop screws and lugs on the pans andmachine frame, and the drive linkage for the pans includes a resilientcoupling which permits the drive to proceed after the pan is positivelystopped by the screws and lugs, and whereby the pans are held in thisposition by the resiliency of said coupling to account for any play orbacklash between the pans and their driving linkage.

And another object is to provide a reversible motor drive for said paninterchange mechanism which is started by manual operation of a switchand which is automatically stopped when a coating pan reaches thecoating position.

The novel features that I consider characteristic of my invention areset forth with particularity in the appended claims. The inventionitself, however, both as to its organization and its additional objectsand advantages thereof, will best be understood from the followingdescription of a specific embodiment when read in connection with theaccompanying drawings in which,

Fig. 1 is an end view of a preferred embodiment of the driving mechanismfor the coating pan interchange mechanism.

Fig. 2 is a vertical cross-section showing one end of the paninterchange mechanism, and particularly the guide tracks for the pan andthe lever and linkage system for moving said pan in said guide tracks.

Fig. 3 is a front view, partly in section, of the complete interchangemechanism.

Fig. 4 is an enlarged detail of a portion of Fig. 2, and showing thecooperation between adjustable stops on the pan supporting brackets andlugs on the machine frame to accurately position the pans in the coatingposition, and

Fig. 5 is a vertical section taken substantially on line 55 of Fig. 4.

Like reference characters refer to corresponding parts throughout thedrawings.

In general, the present invention comprises the provision of twoseparate coating pans which are so mounted on the machine frame as to besimultaneously interchanged between a ready position and the coatingposition. The pans are supported and moved by a lever and linkagemechanism which is in turn set in motion by a cam driven by a reversiblemotor. The contour of the cam is such as to impart a uniformlyaccelerating and decelerating motion to the pans in moving to thecoating position so that agitation of the solution in the pan isnegligible. To further reduce the possibility of such agitation of thecoating solution the pans and the operating lever and linkage thereforare statically balanced, and the slope angle, relative spacing and uppercurved ends of the guide tracks for the pans are carefully selected. Thepans are located in a definite coating position through the cooperationof adjustable stop screws on the pan supporting brackets with lugs onthe machine frame, and the operating mechanism for the pans including aresilient coupling to account for the action of the'pan positioningmeans.

For purposes of disclosure I have shown my coating pan interchangemechanism in association with a coating machine of the immersion typefor which it was particularly designed, but it will be understood bythose skilled in the art that it could be used in connection with otherwell-known coating procedures, such as the applicator or pick-up rolltype, if desired.

In the immersion method of coating, the web to be coated is fed over aroller, immersed in the supply of coating solution held in the coatingpan, and the coating is prevented from contacting the back of the web bythe use of safe edge cups, or the like, as is well known. In accordancewith the present invention, the coating apparatus is provided with atleast two coating pans l0 and I0 which are each movable between thecoating position and a ready position rapidly and simultaneously. In thedrawings, particularly Fig. 2, the coating pan [0 is shown in thecoating position and in which position the conventional immersion roll II, about which the web W to be coated is fed, is immersed in the coatingsolution. The other coating pan I0 is shown in its ready position whichis below and to the right of the coating position, and in which positionit can be readily cleaned and refilled ready for use while the coatingoperation is proceeding from pan I0. When it is desired to change thecoating solution for any reason, the interchange mechanism hereinafterdescribed is operated whereupon pan Ill moves to its ready positiondotted l6 (looking at Fig. 3).

4 left of the coatingposltion, while at the same time pan 10 with itssupply of new solution moves to the coating position.

As is well known to those skilled in the art, the quality, andparticularly the thickness, of the coating applied to the web varieswith the depth of immersion of the roll H into the coating supply, and,therefore, upon the level of the coating supply being maintainedconstant and undisturbed. Therefore, the coating pan being moved intocoating position must be moved in such a manner that the surface of thecoating supply therein is not agitated in any way because the web movescontinuously during the pan interchange and coating starts immediatelyupon the solution in the pan touching the web. This problem becomes moreimpressive when it is considered that this interchange of pans must bemade very rapidly to cut the amount of uncoated web to a minimum. Thepan interchange mechanism I have invented, and will now describe, hasbeen designed to interchange the coating pans in two seconds withoutcausing an agitation in the surface of the coating solution which can bedetected by examining the quality of the coating applied to the web.

To either end of each pan is fastened, in any suitable manner, as bywelding, a supporting bracket l2 of the shape best shown in Figs. 2 and4. Each of the supporting brackets carries a pair of supporting rollersI3 which travel in inclined guide tracks or grooves I4 located in guideplates [5 mounted solidly on the vertical machine frames l6. These guidetracks serve to guide the coating pans between the coating position andtheir respective ready position, and it is pointed out that while themajor portion of each track is straight the upper end of each track iscurved upwardly on a comparatively short radius termi nating in a veryshort section of vertical track. By this arrangement the final incrementof motion of the pan moving into coating position, before it comes torest, is vertical. The are of motion ending in a vertical motion is partof the control exercised over the liquid in the pan to prevent agitationthereof.

The two coating pans are moved simultaneously from one end of the guidetracks to the other end, or to and from the coating position, by asimple lever and linkage arrangement which is rugged and positive inaction, desgned to facilitate smooth and easy motion of the pans, and,adaptable to accurate positioning of the pans in the coating position.This lever and linkage arrangement includes a main operating shaft l1extending horizontally below the coating pans and having its oppositeends journaled in the machine frames [6. Located on shaft I! in spacedrelation are two bellcranks l8. One arm IQ of each bell crank has a link2a pivoted thereto and a supporting bracket 2 for pan l0, while theother arm 2| of each bellcrank has a link 22 pivoted thereto and asupporting bracket l2 of the pan H). A rotation or oscillation ofapproximately 60 degrees of the shaft I! in either direction moves theone pan from coating position to its ready position and simultaneouslymoves the other pan from its ready position to the coating position.

The driving means for the main shaft ll comprises a cam disk 33rotatably mounted on a stubshaft 24 mounted on the left-hand frame Thiscam disk 23 has a compound spiral cam groove 25 in its face the linepositioned mm. 2) below and to the rise "1" of which. see Fig. 1, issufficient to cause an oscillation of shaft II which will shift the twocoating ans between their ready positions and the coating position. Thecam is connected to the shaft I1 by a lever 28 mounted on the shaft andincluding a follower on its free end in the form of a roller 21 whichextends into the cam groove 25.

On the periphery of the cam disk 23 there is fixed a ring gear 28 whichmeshes with a spur gear 29 mounted on the shaft of a reversible electricmotor M which is operated-by a doublethrow switch 30. The respectivecircuits of the motor include normally closed limit switches 3| and 32which are adapted to be opened by moving a roller carrier arm 33,forming a part thereof, to open the switch and break the motor circuit.Also adjustably mounted on the face of said cam disk is a limit switchoperating plate 34 which extends beyond the periphery of the disk by asuillcient amount to contact the arms 33 of the limit switches to openthe same.

When the main motor switch so is thrown to the position shown in Fig. l,the circuit containi limit switch 3| is energized and the cam is rotatedcounterclockwise by the motor M driving through the gears. This drivecontinues until the limit switch operating plate 34 opens the limitswitch 3i to stop the motor (the condition shown in Fig. l) which isjust before the follower 21 reaches the inner end of the cam groove; andby this time the coating pan It has been moved to its coating position.When the motor switch 30 is operated to close the other motor circuit(containing limit switch 32) the motor is started in the other directionand the cam rotates in a clockwise direction until the limit switchoperating plate 34 opens limit switch 32 which stops the 'motor justbefore the follower 21 reaches the other end of the cam groove 25. Sucha motion of the cam would cause the pan- If! to be moved to its readypositionand would cause the pan Ill to be moved to the coating position.

The curve of the cam groove is designed to move the coating pans in sucha manner that the sway of liquid generated by the accelerating motion asthe pans start is counteracted and eliminated by the decelerating motionas the pan stops. The curve of the cam groove is such that the maximumacceleration and velocity of the pans is found at the intermediateportion of their travel between their two positions and the rise ofthe'portion of the groove adjacent each end is very slight so that thepans in moving into coating position actually are traveling at a veryslow rate. This eliminates a sudden stopping of the pan moving intocoating position which would set up an agitation of the solution in thepan. With the arrangement shown it is possible to interchange thecoating pans in the short time of two seconds without causin anoticeable agitation of the solution in the pans.

It will be appreciated that provision must be made for continuallyadding to th coatin supply in the coating pan which is in coatingposition as the web takes it away in order to maintain the level of thesolution in the pan constant. Such a source of coating supply must alsobe available in order to fill the pan which is in ready position. Whenthe coating is of a certain type it may be necessary to continually keepit at a constant temperature in which case the coating pan will have tobe water-jacketed and be continually fed with a thermostaticallycontrolled supply of water. In any case, since these features constituteno part of the present invention it has not been deemed necessary toencumber the present drawings and specifications with such a disclosure.It will suffice to say that it has been found satisfactory to provideeach of the two coating pans with independent and flexible feed lines ofany nature that might be desired and to move the complete unit betweenthe ready and coating positions. In this connection, means are providedfor automatically cutting off the services of the lines on the one panas it leaves the coating position, and cutting on the services of thelines on the other pan as it moves into the coating position.

In the immersion method of coating it is imperative to a uniformgiventhickness of coating that the immersion roll be immersed a given amountin the solution of the pan. This, therefore, means that the coatingposition of pans must be accurately controlled. Since it would beimpractical from a mechanical point of view to depend upon the camgroove and associated linkage to accurately position the pans in thecoating position the following structure is provided for this purpose.

On each end frame I 6 there is located two stop lugs 36 into engagementwith which a pair of for.

adjustable stop screws 31 carried by the pan supporting brackets I2 cometo definitely locate the pans as they move into the coating position. Byinitially adjusting the height of the screws 31 the pans can beaccurately leveled and in the same way a play in the driving mechanismdue to wear or the like can be taken up and accounted The parts are sodesigned and the screws so adjusted that the pans always reach theircoating position just before the cam drive stops and always before thecam follower reaches the end of the cam groove. To permit this conditionto exist without distorting the linkage or stalling the motor, aresilient coupling is introduced in the pan changing mechanism betweenthe cam and the links engaging the same. One form oi resilient couplingwhich serves the desired purpose and is very simple is that shown inFig. 2. The bell cranks iii are each rctatab y mounted on a shaft ii andare connected thereto by a pair of leaf springs 38, one adjacent eachend of the pan, which are each fixed at one end 39 to the shaft andextend radially therefrom between two rollers 40 and 4! fixed to andextending from a web 42 connecting the two arms of the bellcrank. Thus,as the shaft is rotated clockwise by the cam, the spring 38 will pressagainst roller 45 and drive the bellcrank to the right to move pan illinto the coating position, as s own in Fig. 2, and in the oppositedirection the spring acts against roller 40 to drive the other coatingpan into coating position. The springs 38 should be of such gauge orstrength as to act as rigid driving members so long as the coating pansare free to move, but just as soon as the pans are positively stoppedand located in the coating position by the engagement between theadjustable stop screws 31 and lugs 36 the slight over-travel of the camdrive causes the springs to flex, as indicated by the d tted lineposition in Fig. 2. This resilient coupling, therefore, in addition topermitting a slight over-travel in the cam drive, and an accuratepositioning of the coating pans in the coating position, acts tonormally urge the stop screws against the stop lugs and thereby accountfor any play which might appear in the linkage between the links 20 andthe coating pan supporting brackets and bellcrank arms.

The same resilient coupling action could be obtained by placing aresilient coupling between the lever 26 and the shaft I! if desired, butthe present arrangement has been shown because of its simplicity. Thismodified arrangement would consist of rotatably mounting the lever 26 onthe shaft I], rather than keying it thereto as in the presentarrangement, providing a second lever keyed to the shaft l1 andinserting a resilient coupling between these two levers which would actas a rigid coupling up to a load encountered by free movement of thepans, but which would give when the pans were positively obstructed intheir movement as by the engagement between the adjustable screws 31 andthe lugs 35.

The design of the levers, links, tracks and supporting brackets is suchthat there is a balance of forces, due to the weight of the pans and allworking parts, when expressed as a resultant torque on the shaft 11.This balance is maintained in all positions of the two pans except theirstationary position, when the ready pan exerts approximately per centmore torque on the shaft l'l than the pan in the coating position. Thedesign of all parts is also such as to secure the minimum of backlash orlost motion. The location of the rollers i3 carrying the weight of thepans is such that force is exerted on the tracks by the rollers to forma couple in all positions, and hence there can never be any backlash atthese positions.

Referring to Figs. 2 and 3, it will be noted that when one of the pansis in the coating position the rollers l3 on the brackets i2 do not comecompletely to the end of the guide tracks 14. This indicates that thetracks are not supporting the pan which is in the coating position, butthe weight of the pan is suppcrted solely by the link 20 or 22 and thearm of the bellcrank to which it is connected. In this position, thesides of the tracks merely support the pan against sidewise movement. Itwill thus be seen that the force of gravity will tend to move the panfrom coating position the moment the cam drive is started so that thestarting load on the motor will be reduced to a minimum. Thisarrangement of parts, therefore, gives a smooth, steady motion to thepan in both directions and requires a relatively low power output of themotor considering the total mass under motion. steadiness of the loadtends to eliminate all minute fluctuations in velocity which might causeripples in the surface of the coating solution.

From the above description it will be appreciated that four factors havebeen taken into consideration in the design of this equipment which incombination contribute to the resultant motion of the coating pans fromtheir ready position to the coating position with a negligible agitationof the solution in the pans despite a rapid interchange. They are: (1)static balancing of the pans and operating linkage therefor, (2)practical elimination of all play in the mechanism due to wear andmachining tolerances, (3) the slope angle, relative spacing and curvedupper end of the guide tracks, and (4) the uniformly accelerating anddecelerating motion imparted to the pans by the compound curve of thecam groove.

although I have shown and described certain specific embodiments of myinvention, I am fully aware that many modifications thereof arepossible; My invention; therefore, is not to be limited to the precisedetails of construction shown and described but is intended to cover allmodi- 8 flcations coming within the scope of the an pended claims Havingthus described my invention, what I claim is new and desire to secure byLetters Patent of the United States is:

1. In a web coating apparatus the combination of a pair of coatin pansadapted to contain a supply of coating solution and each movable betweena common coating position and a ready position, and means for rapidlyand simultaneously moving one of said pans from the coating position toits ready position while moving the other pan from its ready position tothe coating position without causing an agitation of the liquid level ofthe solution in the pan moving into coating position suflicient toaffect the quality of the coating applied to the web.

2. A coating apparatus according to claim 1, including two sets ofstationary tracks. one set for each pan, and rollers associated witheach pan engaging the set of tracks corresponding to said respectivepans for guiding the pans between the coating position and their readyposition.

3. A coating apparatus according to claim 1 in which the ready positionof each pan is to one side of and below the coating position; one set ofinclined tracks for guiding one pan between its ready position and thecoating position; a second set of inclined tracks for guiding the otherpan between its ready position and the coating position; rollersassociated with each pan to move therewith, the rollers associated withone pan engagin one of said sets of tracks and the rollers associatedwith the other pan engaging the other set of tracks; the upper end ofeach track terminating in a portion which is vertical, whereby the finalincrement of motion of the pans before coming to rest in the coatingposition is vertical to assist in preventing agitation of the liquidlevel of the solution in the pans.

4. A coating apparatus according to claim 1 including two sets ofinclined tracks for guiding the pans between their ready position andthe coating position; one set of tracks for each pan; rollers associatedwith each pan to move therewith and engaging the set of trackscorresponding to the pan with which they are associated; an oscillatablebell crank; a link pivoted between the end of one arm of said crank andone pan, and a link pivoted between the end of the other arm of saidcrank and the other pan; and means for oscillating said bell crankbetween two positions to move said pans to and from said coatingposition.

5. A coating apparatus according to claim 1 including two sets ofinclined tracks for guiding the pans between their ready position andthe coating position; one set of tracks for each pan; rollers associatedwith each pan to move therewith and engaging the set of trackscorresponding to the pan with which they are associated; an oscillatablebell crank; a link pivoted between the end of one arm of said crank andone pan, and a link pivoted between the end of the other arm of saidcrank and the other pan; and a reversible electric motor for oscillatingsaid bell crank between two extreme positions in each of which oppositeones of said pans are moved into the coating position.

6. A coating apparatus according to claim 1 including two sets ofinclined tracks for guiding the pans between their ready position andthe coating position; one set of tracks for each pan;

rollers associated with each pan to move there- 9 with and engaging theset oi tracks corresponding to the pan with which they are associated;an osc llatable bell crank; a link pivoted between the end of one arm ofsaid crank and one pan. and a link pivoted between the end of the otherarm of sa d crank and the other pan; and a reversible electric motor foroscillating said bell crank between two extreme pos tions in each ofwhich a different one of sa d pans is moved into the coating position. amanual switch for starting said motor; and means for automaticallybreaking the motor circuit when one of the coating pans reaches thecoating position.

'7. A coating apparatus according to cla m 1 includin two sets 01'inclined tracks for guiding the ans between their ready position. andthe coating position: one set of tracks for each pan; rollers assoc atedwith each pan to move therewith and engaging theset of tracks corresonding to the can with w ich th y are associated: an osc llatable bellcrank; a link pivoted between the end of one arm of sa d crank and onepan, and a link pivoted between the end of the other arm of sa d crankand the other pan: and means for oscillating said bell crank between twopositions to move said pans to and from said coat ng po ition, said lastment oned means be ng' such as to give the pans a decelerating mot on asthey come to a stop to counteract the sway generated in the liquid bythe accelerated motion as the pans start to move.

8. A coating apparatus according to claim 1 including two sets ofinclined tracks for guid'ng the pans between their ready position andthe coatng position; one set of tracks for each pan; rollers associatedwith each pan to move therewith and engaging the set of trackscorresponding to the pan with which they are associated; an osc'llatablebell crank; a l nk pivoted between the end of one arm of said crank andone pan. and a link pivoted between the end of theot-her arm of saidcrank and the other pan; and means for oscillating said bell crankbetween two positions to move said pans to and from said coating postion, said last mentioned means including an osc'llatable cam thecontour of wh ch is such as to give the pans a decelerating motion asthey come to a stop in order to counteract the sway generated in theliquid by the accelerated motion as the pans start to move.

9. A coating apparatus according to cla m l. including two sets ofinclined track for guid ng the pans between the'r ready position and thecoating pcsit cnz one set of tracks for each pan; rollers associ tedwith each pan to move therewith and engaging the set of trackscorresponding to the pan with which they are assocated; an oscil atablebell crank; a link pivoted between the end of one arm of said crank andone pan, and a link pivoted between the end of the other arm of sa dcrank and the other pan; and means for oscillating said bell crankbetween two positions to move said pans to and from said coatinposition, said last mentioned means including an oscillatable cam thecontour of which is such as to give the pans a declerating motion asthey stop in order to counteract the sway generated in the liquid by theaccelerated motion as the pans start to move; a reversible motor fordriving said cam in opposite directions; a pair of limit switches insaid motor circuit; and a switch operating member associated with saidcam to move therewith and adapted to alternately actuate said limitswitches to automatically stop said motor when one of said pans is movedto the coating position.

10. A coating apparatus according to claim 1 including two sets ofinclined tracks for guiding the ,pans between their ready position andthe coating position; one set of tracks for each pan; rollers associatedwith each pan to move therewith and engaging the set of trackscorresponding to the pan with which they are associated; an oscillatablebell crank; a. link pivoted between the end of one arm of said crank andone pan, and a link pivoted between the end of the other arm 01' saidcrank and the other pan; and means for oscillatin said bell crankbetween two positions to move said pans to and from said coatingposition, said last mentioned means including an oscillatable shaft towhich said bell crank is fixed to be oscillated thereby; an oscillatablecam; a lever fixed at one end to said shaft and including a follower onthe other end engaging the working face of said cam; the rise of saidcam being such as to oscillate said shaft a sufllcient amount to movesaid pans between their two positions, and the contour of said cam beingsuch as to give the pans a decelerating motion as they stop tocounteract the sway generated in the liquid by the accelerated motion asthe pans start to move.

11. A coating apparatus according to claim 1 including two sets ofinclined tracks for guiding the pans between their ready position andthe coatin position; one set of tracks for each pan;

rollers associated with each pan to move therewith and engaging the setof tracks corresponding to the pan with which they are associated; anoscillatable bell crank; a link pivoted between the end of one arm ofsaid crank and one pan, and a link pivoted between the end of the otherarm of said crank and the other pan; and means for oscillating said bellcrank between two positions to move said pans to and from said coatingposition, said last mentioned means including an oscillatable shaft towhich said bell crank is fixed to be oscillated thereby; an oscillatablecam; a

lever fixed at one end to said shaft and including a follower on theother end engaging the working face of said cam; the rise of said cam beng such as to oscillate said shaft a, sufllcient amount to move saidpans between their two positions, and the contour of said cam being suchas to give the pans a decelerating motion as they stop to counteract thesway generated in the liquid by the accelerated motion as the pans startto move; a reversible motor geared to said cam for driving the same; andmeans for automatically stopping said motor when the cam has been movedsufficiently to cause a coating pan to be moved to the coating position.

12. In a web coating apparatus the combination of a pair of coating pansadapted to contain a supply of coating solution and each movable betweena coating position and a ready position; a pair of stationary inclinedtracks each at opposite ends of one of said pans for guiding said panbetween its ready position and the coating position, a second pair ofstationary inclined tracks each at opposite ends of the other of saidpans for guiding said pan between its two positions; rollers carried byopposite ends of each pan and engaging the pair of tracks correspondingt the pan by which they are carried to movably support the pans on saidtracks; an

oscillatable shaft located vertically below said coating position; apair of bell'cranks fixed to said shaft adJacent opposite ends thereof alink pivoted between the end of one arm of said cranks and one pan, anda link pivoted between the end of the other arm of said crank and theother pan, whereby said pans are caused to be moved along said tracks byan oscillation of said shaft between their ready and the coatingposition; the design of said levers, links, tracks and rollers beingsuch that there is a balance of forces, due to the weight of the pansand all working parts, when expressed as a resultant torque on saidshaft, at all times when the parts are moving; and means for oscillatingsaid shaft to move said pans between their two positions of rest.

13. A coating apparatus according to claim 1 including two sets ofinclined tracks for guiding the pans between their ready position andthe coating position; one set of tracks for each pan; rollers associatedwith each pan to move therewith and engaging the set of trackscorresponding to the pan with which they are associated; an oscillatablebell crank; a link pivoted between the end of one arm of said crank andone pan, and a link pivoted between the end of the other arm of saidcrank and the other pan; and means for oscillating said bell crankbetween two positions to move said pans to and from said coatlngposition, including a shaft oscillatable between two limits and to whichsaid bell crank is pinned; an oscillatable disk having a spiral camgroove in its face the rise of which is suincient to oscillate saidshaft between its two limits of movement; a movable arm mounted on oneend of said shaft and connected to said shaft to oscillate the same asthe arm is moved; a roller on the end of said arm engaging said camgroove; and means for oscillating said disk to bring said roller toopposite ends of said cam groove.

14. A coating apparatus according to claim 1 including two sets ofinclined tracks for guiding the pans between their ready position andthe coating position; one set of tracks for each pan; rollers associatedwith each pan to move therewith and engaging the set of trackscorresponding to the pan with which they are associated; an oscillatablebell crank; a link pivoted between the end of one arm of said crank andone pan, and a link pivoted between the end of the other arm of saidcrank and the other pan; and means for oscillating said bell crankbetween two positions to move said pans to and from said coatingposition, including a shaft oscillatable between two limits and to whichsaid bell crank is pinned; an oscillatable disk having a spiral camgroove in its face the rise of which is sufiicient to oscillate saidshaft between its two limits of movement; a movable arm mounted on oneend of said shaft and connected to said shaft to oscillate the same asthe arm is moved, a roller on the end of said arm engaging said camgroove; and means for oscillating said disk to bring said roller toopposite ends of said cam groove, comprising a reversible electric motorgeared to said disk to drive the same in opposite directions; a manualdouble-throw switch in the motor circuit for instlgating the drive inopposite directions; a pair of normally closed limit switches in themotor circuit, includin operating arms extending to a point adjacent theperiphery of said disk; and an actuating plate mounted on said disk andadapted to engage alternate ones of said switch arms depending upon thedirection of movement of said disk to stop the motor drive when one ofthe pans has been moved to the coating position.

15. In a web coating apparatus the combination of a supporting frame; apair of coating pans adapted to contain a supply of coating solution;means for mounting sai ans on said frame so that each pan is movablebetween a coating position and a ready position; means forsimultaneously moving said pans between their two positions in oppositerelation, whereby one pan is moved to the coating position at the sametime the other pan is moved from the coating position to its readyposition; cooperating adjustable stop screws and abutments on said frameand coating pans to accurately position each of said pans in a definitecoating position; said means including an oscillatable driving shaft; alinkage between said shaft and said pans causin said pans to besimultaneously shifted between their two positions by an oscillation ofsaid shaft; a driving cam; a driving linkage between said cam and shaftwhereby the rise of said cam determines the degree of movement of saidshaft; one of said linkages including a resilient coupling which willgive only when said cooperating stop screws and lugs on said frame andpans engage, whereby said pans are definitely located and resilientlyheld in the coating position by said cooperating stop screws and lugsand all back lash and play is eliminated from said driving connectionand linkage while a pan is in the coating position.

16. An apparatus according to claim 15 in which said resilient couplingincludes a spring connecting a driven and driving part of said linkagesand being of such gauge as to act as a rigid power transmitting memberso long as the pans are free to move and adapted to flex when thecooperating stop screws and lugs come into engagement.

LEON P. MOREY.

REFERENCES CITED UNITED STATES PATENTS Name Date Number Roby May 10,1927

